1st ICAI 2020

International Conference on Automotive Industry 2020

Mladá Boleslav, Czech Republic

Figure 7: Tensile shear strength of adhesively bonded PLA, PET and PP (pre-treatment: metal – sand blasting, plastic – Atmospheric pressure plasma (left); fractured surfaces: from top to bottom: PLA, PET, PP (right)

Source: own elaboration 4. Conclusion

The results show that bio-origin-PLA is, also from the manufacturing standpoint, a good potential alternative for petro-chemical plastics. It can similarly be joined with metals using established methods, achieving moderate to good strength. As with standard plastics, the influence of pre-treatment is strong: By optimizing the its type and parameters, joint strengths of up to 5,7 N/mm² for adhesive bonding and 17 – 23 N/mm² for thermal direct joining were reached. For adhesive bonding PLA is (due to its lower surface energy) not yet in league with plastics like PP, but achieves even slightly better results than PET. The thermal direct joining process exhibited the best joint strength levels when a micro-form-fit was incorporated with the help of laser-based surface pre-treatment. As a result, it is not only superior to adhesive bonding in production time (as final load capacity is reached in seconds instead of minutes or hours) but also in strength. This opens new, more ecological and efficient ways to join difficult-to-bond thermoplastics like PLA in the future. Hopefully these findings help to establish a better understanding of eco-friendly materials and promote the use of sustainable materials in industrial production. Acknowledgements Part of the work was co-financed by funds from the European Union, based on decisions of the parliament of Saxony, Germany.

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